As a key technology of the Next Generation Network (NGN), the Multi-Protocol Label Switching (MPLS) technology plays a more and more important role in the IP network. If packets are forwarded through label switching in an MPLS network, the network route may be controlled flexibly. Label switching is also applied widely in traffic engineering, Virtual Private Network (VPN), Quality of Service (QoS) control, and so on. The path for forwarding packets in an MPLS network is called a Label Switching Path (LSP).
With the MPLS technology being widely applied in the multi-service bearer of the IP network, traffic switching of the MPLS network becomes an important subject, and is involved in detecting a network fault and creating a traffic protection path. Therefore, the improvement of the traffic switching technology is critical to improving the availability and stability of the MPLS network, and preventing interruption of network traffic.
After an LSP is created in the MPLS network, traffic switching occurs when the user modifies the tunnel configuration of the MPLS Traffic Engineering (MPLS TE) or performs Fast ReRouting (FRR) switching. The method of MPLS network traffic switching in a conventional art includes: sending, by a control plane of a router, an uplink forwarding entry also known as an Incoming Label Mapping (ILM) and a downlink forwarding entry also known as a Next Hop Label Forwarding Entry (NHLFE) to a forwarding unit immediately after a new LSP is created successfully; at the same time, replacing ILM entries and NHLFE entries existent before switching; switching the traffic to the new LSP; and deleting, by the control plane, the LSP existent before the switching, thus finishing the traffic switching.
The NHLFE is used to describe the operations performed by the router for the label, including pushing, popping, and switching. The ILM is a process of mapping the label to the NHLFE performed by the label switching router. On each label switching router of the LSP, a mapping entry of the mapping between the input label and the output label is maintained. For a received label packet, the label switching router needs only to find the corresponding NHLFE according to the ILM entry, and then forward the packet.
In the method of MPLS network traffic switching in the conventional art, the sending of the ILM entry may be asynchronous to the sending of the NHLFE entry, thus causing transient interruption of the traffic. If the sending of the ILM entry is faster than the sending of the NHLFE entry, the following phenomenon may occur in a very short period: The NHLFE entry before switching is not replaced but the ILM entry before switching is already replaced with a new ILM entry. If such a phenomenon occurs, the old NHLFE entry is not available for matching the new ILM entry before the NHLFE entry is replaced, and the traffic may be interrupted transiently. Besides, the upstream node forwarding entry is asynchronous to the downstream node forwarding entry, which also causes transient interruption of the traffic. If the traffic of the upstream node is switched to the new LSP before the downstream node forwarding entry is sent completely, the traffic may also be interrupted transiently. Traffic interruption deteriorates the availability and stability of the network seriously.